Fluid end with selectively coated surfaces

ABSTRACT

A fluid end includes a block, a suction bore formed in the block and having a suction valve disposed within the suction bore, and a discharge bore formed in the block and having a discharge valve disposed within the discharge bore. The fluid end also includes a plunger bore formed in the block and having a plunger disposed therein, the plunger moveable in a first direction and a second direction opposite the first direction such that the plunger draws fluid through the suction valve when the plunger moves in the first direction and forces fluid through the discharge valve when the plunger moves in a second direction. The fluid end further includes a seal pack configured to maintain sealing contact with the plunger as the plunger moves in the first direction or the second direction and a coating applied to the block between the seal pack and the block.

TECHNICAL FIELD

The present disclosure relates to a fluid end for a fluid system. Specifically, the present disclosure relates to a coating that is applied to selected portions of a fluid end of a hydraulic fracturing system (or other well-service system) to improve the durability of the fluid end, as well as reduce required maintenance during the usable life of the fluid end.

BACKGROUND

Various types of fluid conduit are in widespread use in a variety of industries. For example, fluid conduit may be used in a variety of applications in the petroleum industry. One such application includes hydraulic fracturing, which is a well stimulation technique that typically involves pumping hydraulic fracturing fluid into a wellbore at a rate and pressure sufficient to form factures in a rock formation surrounding the wellbore. This well stimulation technique often enhances the natural fracturing of a rock formation in order to increase the permeability of the rock formation, thereby improving recovery of water, oil, natural gas, and/or other fluids. In order to fracture such rock formations, the hydraulic fracturing fluid is injected into the wellbore at pressures and rates sufficient to exceed a fracture gradient of the target formation. In some conventional arrangements, a series of pumps is used to pressurize the hydraulic fracturing fluid within a fluid end which then distributes the pressurized hydraulic fracturing fluid to a fracturing manifold. The fracturing manifold receives the pressurized hydraulic fracturing fluid from the pumps and delivers the hydraulic fracturing fluid to an injection point (e.g., a frac tree) at the necessary pump rate.

In these types of applications, the hydraulic fracturing fluid (in the form of a slurry), having hard proppant particles therein, is pressurized to high pressures, such as 15,000 pounds per square inch (psi). As slurry is compressed in the fluid end, the fluid end is subject to high levels of abrasion due to the highly pressurized slurry and is subject to high pressure differentials as the hydraulic fracturing fluid is compressed in the fluid end. Excessive wear of the fluid can lead to reduced lifetimes of the conduit. Increased frequency of maintenance and/or reduced lifetime of the fluid end can result in reduced levels of uptime of processes reliant on the fluid end.

An example fluid end is described in U.S. Patent Publication Application No. 2020/0182240A1 (hereinafter referred to as the '240 reference). In particular, the '240 reference describes a flangeless fluid end. The '240 reference describes various configurations that are designed to transfer wear from a body of a fluid end to removeable components of the fluid end. For examples, the '240 reference describes a seal that is located within a groove in the body of the fluid end and contacts a discharge plug. The '240 reference explains that erosion wear is transferred from the body of the fluid end to the discharge plug in such a configuration that the discharge plug can be replaced once erosion of the discharge plug occurs. The '240 reference also notes that transferring erosion wear to replaceable components can reduce the cost associated with repairing or replacing the body of the fluid end.

However, while the '240 reference describes transferring erosion wear to various components of the fluid end that can be easily replaced, the system described in the '240 reference does not describe reducing, slowing, or otherwise inhibiting wear that is experienced by various components within the fluid end. As a result, the '240 reference could be subject to increased maintenance due to the need to replace parts that experience wear that has been transferred by the configuration described in the '240 reference. Such increased maintenance could result in increased down time of the fluid end and/or increased costs associated with maintenance and replacement parts.

Example embodiments of the present disclosure are directed toward overcoming the deficiencies described above.

SUMMARY

An example fluid end includes a block, a suction bore formed in the block and having a suction valve disposed within the suction bore, and a discharge bore formed in the block and having a discharge valve disposed within the discharge bore. The fluid end also includes a plunger bore formed in the block and having a plunger disposed therein, the plunger moveable within the plunger bore in a first direction and a second direction opposite the first direction such that the plunger directs fluid through the suction valve when the plunger moves in the first direction and directs fluid through the discharge valve when the plunger moves in the second direction. The fluid end further includes a seal pack disposed within the plunger bore and between the plunger and the block, thereby forming a fluid seal between the plunger and the block, the seal pack configured to maintain sealing contact with the plunger as the plunger moves in the first direction or the second direction and a coating disposed on a surface of the block within the plunger bore between the seal pack and the block.

An example fluid end includes a block, a suction bore formed in the block on a first axis, a discharge bore formed in the block on the first axis, and a plunger bore formed in the block on a second axis that is substantially perpendicular to the first axis. The fluid end also includes a pump chamber formed at least partially between the suction bore, the discharge bore, and the plunger bore, and a coating applied to the block and applied within at least a portion of the suction bore, at least a portion of the discharge bore, and at least a portion of the plunger bore.

In a further example, an example fluid system includes a fluid block, and a plunger bore formed in the fluid block and having a plunger disposed at least partially within the plunger bore, the plunger being moveable in a first direction and a second direction opposite the first direction. The fluid system further includes one or more seals disposed between the fluid block and the plunger, the one or more seals configured to maintain sealing contact with the plunger as the plunger moves in the first direction or the second direction, and a coating applied to the fluid block between the one or more seals and the fluid block.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partial schematic view of an example fluid system having a fluid end in accordance with an example of the present disclosure.

FIG. 2 is a cross-sectional view of an example fluid end in accordance with an example of the present disclosure.

FIG. 3 is a cross-sectional view of an example fluid end block in accordance with an example of the present disclosure.

FIG. 4 is a flowchart illustrating a method of selectively coating portions of a fluid end in accordance with an example of the present disclosure.

DETAILED DESCRIPTION

FIG. 1 depicts an example fluid system 100. The fluid system 100 shown in FIG. 1 is part of a well service, workover, or well stimulation system for an oil and gas well. For example, the fluid system 100 is implemented in a hydraulic fracturing system, which is a well stimulation technique that involves pumping hydraulic fracturing fluid into a wellbore at a rate and pressure sufficient to form fractures in a rock formation surrounding the wellbore. In some examples, the fluid system 100 shown in FIG. 1 forms a portion of a hydraulic fracturing system or other well service system and may include additional and/or alternative components than the components shown and described in FIG. 1 .

In some examples, the fluid system 100 includes at least one motor 102 coupled to a pump 104. The motor 102 is coupled to the pump 104 and is configured to drive operation of the pump 104. In some examples, the motor 102 may be a diesel engine or other type of internal combustion engine. Alternatively, the motor 102 may be an electric motor. In either example, the motor 102 may be directly or indirectly coupled to the pump 104 and may be configured to drive the pump 104.

In some examples, the pump 104 may be a hydraulic fracturing pump (or other type of well service or workover pump). The pump 104 may include various types of high-volume hydraulic fracturing pumps such as triplex pumps, quintuplex pumps, or other types of hydraulic fracturing pumps. Additionally, and/or alternatively, the pump 104 includes other types of reciprocating positive-displacement pumps or gear pumps. A number of pumps implemented in the fluid system 100 and designs of the pump 104 (or pumps) may vary depending on the fracture gradient of the rock formation that will be hydraulically fractured, the number of pumps 104 used in a fluid system 100, the flow rate necessary to complete the hydraulic fracture, the pressure necessary to complete the hydraulic fracture, etc. The fluid system 100 includes any number of pumps 104 in order to pump hydraulic fracturing fluid at a predetermined rate and pressure. The exact configuration of the fluid system 100 varies from site to site.

The pump 104 includes at least one plunger 106 that is at least partially disposed within a fluid end 108. In some examples, the pump 104 includes multiple plungers 106 disposed within the fluid end 108. When the pump 104 is operating, the pump 104 drives the plunger 106 in reciprocating motion. For example, the pump 104 moves the plunger 106, at least partially within the fluid end 108, in a first direction 110 and a second direction 112. In some examples, the pump 104 may be configured to move the plunger 106 in reciprocal directions in order to draw fluid into the fluid end 108, compress the fluid within the fluid end 108, and pump the fluid out of the fluid end 108. For example, when the pump 104 moves the plunger 106 in the first direction 110, the plunger 106 draws fluid through a valve (shown in FIG. 2 ) into the fluid end 108 from a fluid source 114. The fluid source 114 includes a fluid manifold configured to distribute hydraulic fracturing fluid to one or more fluid ends and corresponding pumps that are implemented in a hydraulic fracturing system. Additionally or alternatively, the fluid source 114 include one or more water tanks, hydration units, liquid additive systems, etc.

Furthermore, when the pump 104 moves the plunger 106 in the second direction 112, the plunger 106 compresses the fluid in the fluid end 108 until the fluid reaches a predetermined pressure. Once the fluid is compressed to the predetermined pressure, a valve (shown in FIG. 2 ) within the fluid end opens and allows the fluid to move from the fluid end 108 to a fluid manifold 116. In some examples, the fluid manifold 116 receives pressurized fluid from one or more fluid ends and directs the fluid to a wellhead 118 where the fluid is injected into a wellbore.

In some examples, the fluid end 108 includes a block 120 having one or more bores (or fluid passages) formed in the block 120 of the fluid end 108. The block 120 may be formed from stainless steel, carbon steel, or other material. In some examples, the fluid end 108 includes a suction bore 122 formed in the block 120. The suction bore 122 provides a fluid passageway for fluid to enter the fluid end 108 when the plunger 106 moves in the first direction 110. The suction bore 122 includes a suction valve (shown and described with respect to FIG. 2 ) disposed within the suction bore 122. The suction valve is configured to control flow of fluid into the fluid end 108. For example, when the plunger 106 moves in the first direction 110, the movement of the plunger 106 causes the suction valve to open, thereby drawing fluid into the fluid end 108. Conversely, when the plunger 106 moves in the second direction 112, the suction valve remains closed, allowing the plunger 106 to compress fluid within the fluid end 108.

The fluid end 108 also includes a discharge bore 124 formed in the block 120. The discharge bore 124 provides a fluid passageway for fluid to be discharged from the fluid end 108 to the fluid manifold 116 (or other component). The discharge bore 124 includes a discharge valve (shown and described with respect to FIG. 2 ) disposed within the discharge bore 124. The discharge valve is configured to control fluid flow from the fluid end 108. For example, the discharge valve remains closed until the fluid has been compressed to a predetermined pressure as the plunger 106 compresses the fluid by moving in the second direction 112. Once the fluid is compressed to the predetermined pressure, the pressurized fluid causes the discharge valve to open, allowing the fluid to be discharged from the fluid end 108.

The fluid end 108 further includes a plunger bore 126 formed in the block 120 of the fluid end 108. The plunger bore 126 is sized to receive the plunger 106 of the pump 104 at least partially therein. As mentioned previously, the plunger 106 is moveable in the first direction 110 and the second direction 112 within the plunger bore 126 to draw fluid into the fluid end 108 via the suction bore 122, compress the fluid, and discharge the fluid from the fluid end 108 via the discharge bore 124. The fluid end 108 further includes a suction cover bore 128 formed in the block 120 of the fluid end 108. The suction cover bore 128 remains sealed during operation of the pump 104. However, the suction cover bore 128 provides access to the plunger 106 or portions of the fluid end 108 for maintenance or other reasons, while the pump 104 is not operating.

The fluid end 108 also includes a pump chamber 130 disposed between the suction bore 122 and the discharge bore 124. The pump chamber 130 is a chamber formed within the fluid end 108 that is formed at least in part by a convergence of the suction bore 122, the discharge bore 124, the plunger bore 126, and the suction cover bore 128. In some examples, the plunger 106 compresses the fluid in the pump chamber 130 to a predetermined pressure, which may cause the discharge valve to open, allowing the fluid to exit the pump chamber 130 via the discharge valve.

The fluid end 108 further includes one or more sealing surfaces 132 (e.g., surfaces 132(1)-132(5) shown in FIG. 3 ). The sealing surfaces 132 are surfaces of the block 120 (e.g., internal surfaces thereof) where one or more seals (shown in FIG. 2 ) are disposed in contact with the block 120. In some examples, the one or more seals are disposed (e.g., radially and/or axially) between one or more components of the fluid end 108 and the block 120 (e.g., disposed between one or more internal components of the fluid end 108 and corresponding internal surfaces of the block 120) of the fluid end 108. Sealing surfaces 132 of fluid ends 108 are often subject to high pressures and abrasive fluids. In some examples, fluids may flow (e.g., in an axial direction) between the seals and the block 120 due to the high-pressure environment of the fluid end 108. As such, the sealing surfaces 132 of the block 120 experience abrasive forces during operation of the pump 104 because of fluid that flows between a seal and a corresponding sealing surface 132 of the block 120. Such abrasion could result in washboard failure of the sealing surfaces 132, or other types of failure.

In some examples, a coating 134 may be applied to one or more of the sealing surfaces 132. In some examples, the coating 134 may be applied to each of the sealing surfaces 132 of the fluid end 108. The coating 134 may include a hardness that is greater than the hardness of the material used for the block 120 of the fluid end 108 and may, therefore, resist abrasive forces and/or resist corrosion which may result in a longer usable life, when compared to fluid ends without coating applied to sealing surfaces. In some examples, other surfaces of the block 120 of the fluid end 108 are substantially free of the coating 134. As used herein, a surface that is “substantially free” of coating is a surface to which a coating is not directly or intentionally directly applied, but may still be subjected to some hardening. For example, in a spray-coating hardening process, some overspray may occur on surfaces adjacent to or otherwise proximate surfaces intended to be hardened. However, in some examples, all interior surfaces (e.g., each bore and the pump chamber 130) of the fluid end 108 may be coated in addition to, or instead of, the surfaces described previously.

In some examples, the coating 134 may include a metallic alloy (e.g., formed from a powdered metal alloy). The powdered metal alloy may include at least one of tungsten carbide, cobalt, chromium, or combinations thereof and may include any combination (percentage) of such materials. In some examples, the coating 134 may be a thermal spray coating that is applied using a high velocity air fuel (HVAF) thermal spray process or a high velocity oxygen fuel (HVOF) thermal spray process. Furthermore, the coating 134 may instead be applied via a plating, diffusion, a spray and fuse process, or physical vapor deposition (PVD) process, among other processes. Other techniques, including, but not limited to, plasma twin wire arc, may also be used to apply the coating 134 to the desired surfaces. The process may vary based on the type of material used for the block 120 of the fluid end and/or the type of material used for the coating 134. Any technique that allows for a robust mechanical bond of the coating 134 to the desired surfaces may be used. By including the coating 134 on the sealing surfaces 132, the coating 134 may reduce wear on the block 120, while increasing the resistance of the sealing surfaces 132 to erosive forces caused by pumping a fluid (e.g., hydraulic fracturing fluid or other abrasive slurry) through the fluid end 108.

In some examples, the coating 134 may include any suitable thickness. By way of example, and not limitation, the coating 134 may include a thickness between approximately 0.00001 inches and approximately 0.1 inches. In some examples, the coating 134 may have a thickness between approximately 0.0001 inches and approximately 0.01 inches. Additionally, and/or alternatively, the coating 134 may have a thickness between approximately 0.001 inches and approximately 0.009 inches. In further examples, the coating 134 may include a thickness greater than or less than the example ranges described previously. Furthermore, the coating 134 may be substantially uniform in thickness. Moreover, the coating 134 may have a suitable surface finish. For instance, the coating 134 on the sealing surfaces 132 may have a desirable finish (e.g., a smooth and/or homogeneous surface finish to ensure that the coating 134 does not include cracks, rough patches, or other inconsistencies that may be particularly disposed to erosion). In examples, a thermal spray technique such as HVAF and/or HVOF may result in a desired surface finish without requiring subsequent finishing, polishing, or the like. Furthermore, the coating 134 may be applied to additional or fewer surfaces of the fluid end 108 than described herein.

In some examples, by selectively applying the coating 134 to one or more of sealing surfaces 132, the useful life of the block 120 of the fluid end 108 may be significantly increased and/or down time due to maintenance may be decreased. Furthermore, by applying the coating 134 to the sealing surfaces 132 while excluding other surfaces, cost associated with the coating 134 may be minimized, while potentially increasing the useful life of the block 120. Moreover, the coating 134 may be reapplied to the sealing surfaces 132, thereby further increasing a usable life of the block 120 of the fluid end 108.

FIG. 2 depicts a cross-sectional view of the fluid end 108 and components thereof. The fluid end 108 shown in FIG. 2 may be substantially similar to and/or the same as the fluid end 108 shown and described in FIG. 1 . In some examples, the fluid end 108 includes the block 120 having one or more bores formed in the block 120 of the fluid end 108. For example, the fluid end 108 includes the suction bore 122 formed in the block 120 along a first axis 200. In some examples, the suction bore 122 may provide a fluid passageway extending from an exterior surface of the block 120 to the pump chamber 130. The suction bore 122 allows fluid to enter the fluid end 108 when the plunger 106 moves in a first direction 110, drawing fluid into the pump chamber 130 of the fluid end 108. The suction bore 122 includes a suction valve 202 disposed within the suction bore 122 that is configured to control fluid flow through the suction bore 122. The suction bore 122 also includes a suction valve seat 204 disposed within the suction bore 122. The suction valve seat 204 provides a surface against which the suction valve 202 rests when the suction valve 202 is closed. That is, when the plunger 106 moves in the first direction 110, the plunger 106 creates sufficient suction within the pump chamber 130 to unseat (e.g., lift) the suction valve 202 to open the suction valve 202 thereby drawing fluid into the pump chamber 130.

In some examples, the suction valve seat 204 may include an annular seal 206 (e.g., seal, O-ring, gasket, etc.) disposed in contact with the suction valve seat 204 and the suction bore 122 of the block 120. The seal 206 is configured to form a fluid seal between the suction valve seat 204 and the block 120. However, as described previously, fluid may flow between the seal 206 and the block 120 due, at least in part, to the cyclic high-pressure environment experienced within the fluid end 108 during operation of the pump 104. As such, the coating 134 (shown and described in FIG. 1 and further shown in FIG. 3 ) may be applied to the suction bore 122 between the seal 206 and the block 120 to prevent, reduce, slow, and/or otherwise inhibit wear that may be caused by fluid that flows between the seal 206 and the suction bore 122 of the block 120.

The fluid end 108 further includes a discharge bore 124 formed in the block 120 along the first axis 200. The discharge bore 124 forms a fluid passageway extending between an exterior surface of the block 120 and the pump chamber 130. The discharge bore 124 allows fluid to be discharged from the fluid end 108 to a fluid manifold 116 via an outlet 208 of the fluid end 108. The discharge bore 124 includes a discharge valve 210 disposed within the discharge bore 124 that is configured to control fluid flow through the discharge bore 124. The discharge bore 124 also includes a discharge valve seat 212 disposed within the discharge bore 124. In some examples, the discharge valve seat 212 provides a surface against which the discharge valve 210 rests when the discharge valve 210 is closed. That is, when the plunger 106 moves in the second direction 112, the plunger 106 compresses fluid within the pump chamber 130 until a pressure within the pump chamber 130 reaches and/or exceeds a threshold pressure, thereby forcing the discharge valve 210 to unseat (e.g., lift) opening the discharge valve 210. The plunger 106 directs the fluid out of the outlet 208 of the fluid end 108 and into a fluid manifold or other component.

In some examples, the discharge valve seat 212 includes an annular seal 214 (e.g., seal, O-ring, gasket, etc.) disposed in contact with the discharge valve seat 212 and the discharge bore 124 of the block 120. The seal 214 is configured to form a fluid seal between the discharge valve seat 212 and the block 120. However, as described previously, fluid may, at times, flow between the seal 214 and the discharge bore 124 due, at least in part, to the cyclic high-pressure environment experienced within the fluid end 108 during operation of the pump 104. As such, the coating 134 (shown and described in FIG. 1 and further shown in FIG. 3 ) may be applied to the discharge bore 124 between the seal 214 and the block 120 to prevent, reduce, slow, and/or otherwise inhibit wear that may be caused by fluid that flows between the seal 214 and the discharge bore 124 of the block 120.

In some examples, the discharge bore 124 further includes a discharge cover 216 and discharge cover retainer 218 that are disposed at least partially within the discharge bore 124. The discharge cover 216 causes fluid that flows through the discharge valve 210 to flow out of the fluid end 108 via the outlet 208. Furthermore, a spring 219 (or other type of biasing member) is disposed between the discharge valve 210 and the discharge cover 216. The spring 219 is configured to maintain the discharge valve 210 in a closed position (pictured in FIG. 2 ) until fluid within the pump chamber 130 reaches and/or exceeds a threshold pressure. That is, the spring 219 exerts a force on the discharge valve 210 to maintain the discharge valve 210 in the closed position. Once the fluid is compressed to the threshold pressure, the fluid overcomes the force exerted on the discharge valve 210 by the spring 219. The discharge cover retainer 218 is coupled to the block 120 of the fluid end 108 via threading or other coupling means and is configured to maintain a position of the discharge cover 216 within the discharge bore 124.

In some examples, the discharge cover 216 includes an annular discharge cover seal 220 (e.g., seal, O-ring, gasket, etc.) disposed between the discharge cover 216 and the block 120 of the fluid end 108. The discharge cover seal 220 is configured to form a fluid seal between the discharge cover 216 and the block 120. However, as described previously, fluid may, at times, flow between the discharge cover seal 220 and the block 120 due, at least in part, to the cyclic high-pressure environment experienced within the fluid end 108 during operation of the pump 104. As such, the coating 134 (shown and described in FIG. 1 and further shown in FIG. 3 ) may be applied to the discharge bore 124 between the discharge cover seal 220 and the block 120 to prevent, reduce, slow, and/or otherwise inhibit wear that may be caused by fluid that flows between the discharge cover seal 220 and the discharge bore 124 of the block 120.

The fluid end 108 further includes the plunger bore 126 formed in the block 120 along a second axis 221 that is substantially perpendicular to the first axis 200. The plunger bore 126 is sized to receive a plunger 106 of the pump 104 at least partially within the plunger bore 126. Furthermore, the plunger bore 126 is sized to allow the plunger 106 to move in the first direction 110 and the second direction 112 at least partially within the plunger bore 126 to draw fluid into the fluid end 108 via the suction bore 122, compress the fluid in the pump chamber 130, and discharge the fluid from the fluid end 108 via the discharge bore 124.

In some examples, the fluid end 108 includes a seal pack 222 that is comprised of one or more seals that maintain sealing contact with the plunger 106, even as the plunger 106 moves in the first direction 110 and the second direction 112. As such, the seal pack 222 creates a fluid seal between the plunger 106 and the plunger bore 126. However, as described previously, fluid may, at times, flow between the seal pack 222 and the plunger bore 126 due, at least in part, to the cyclic high-pressure environment experienced within the fluid end 108 during operation of the pump 104. As such, the coating 134 (shown and described in FIG. 1 and further shown in FIG. 3 ) may be applied to the plunger bore 126 between the seal pack 222 and the block 120 to prevent, reduce, slow, and/or otherwise inhibit wear that may be caused by fluid that flows between the seal pack 222 and the plunger bore 126 of the block 120.

The fluid end 108 includes a suction cover bore 128 formed in the block 120 of the fluid end 108 along the second axis 221. In some examples, the suction cover bore 128 includes a suction cover 224 and a suction cover retainer 226 that are disposed at least partially within the suction cover bore 128. The fluid end 108 includes a spring 228 (or other biasing member) disposed between the suction valve 202 and a suction valve retainer 230. The suction valve retainer 230 extends between the spring 228 and the suction cover 224 and is configured to maintain a position of the spring 228 such that the spring 228 exerts a force on the suction valve 202 to maintain the suction valve 202 in a closed position. In some examples, when the plunger 106 moves in the first direction 110, the plunger 106 creates suction within the pump chamber 130 that overcomes the force exerted on the suction valve 202 by the spring 228, thereby opening the suction valve 202.

In some examples, the suction cover 224 includes an annular suction cover seal 232 (e.g., seal, O-ring, gasket, etc.) disposed between the suction cover 224 and the block 120 of the fluid end 108. The suction cover seal 232 is configured to form a fluid seal between the suction cover 224 and the block 120. However, as described previously, fluid may, at times, flow between the suction cover seal 232 and the block 120 due, at least in part, to the cyclic high-pressure environment experienced within the fluid end 108 during operation of the pump 104. As such, the coating 134 (shown and described in FIG. 1 and further shown in FIG. 3 ) may be applied to the suction cover bore 128 between the suction cover seal 232 and the block 120 to prevent, reduce, slow, and/or otherwise inhibit wear that may be caused by fluid that flows between the suction cover seal 232 and the suction cover bore 128 of the block 120.

In some examples, by selectively applying the coating 134 to one or more of sealing surfaces 132 between the respective seals and the block 120, the useful life of the block 120 of the fluid end 108 may be significantly increased and/or down time due to maintenance may be decreased. Furthermore, the coating 134 may be reapplied to the sealing surfaces 132, thereby further increasing a usable life of the block 120 of the fluid end 108.

FIG. 3 depicts a cross-sectional view of the block 120 of the fluid end 108. As shown in FIG. 3 , many of the components shown and described in FIG. 2 have been removed to depict the coating 134 (represented by the stipple shading in FIG. 3 ) and the various surfaces and/or portions of the block 120 to which the coating 134 may be applied. As described previously, the coating 134 may be applied to various sealing surfaces 132 where one or more seals are disposed in contact with the block 120 of the fluid end 108. In some examples, the coating 134 may be applied to each of the sealing surfaces 132 of the fluid end 108. However, the coating 134 may be applied to fewer than all of the sealing surfaces 132 of the fluid end 108, in some examples. Furthermore, other surfaces of the block 120 of the fluid end 108 may be substantially free of the coating 134. However, in some examples, other surfaces of the block 120 may be coated with the coating 134. In some examples, the coating 134 may be applied to the sealing surfaces 132 of the block 120 such that the coating 134 extends past either axial end of a seal or seal pack so as to cover an entirety of a sealing surface 132. In some examples, the coating 134 may extend about 5% or more, such as about 5% to about 25%, such as about 10% to about 20% beyond one or both axial ends of the corresponding seal or seal pack, when measured in relation to an axial length of the corresponding seal or seal pack. In some examples, the coating 134 may extend about 1/32 inch or more, such as about 1/32 inch to about ⅛ inch such as about 1/16 inch to about ⅛ inch beyond one or both axial ends of the corresponding seal or seal pack.

As described previously, the coating 134 may include a hardness that is greater than the hardness of the material used for the block 120 of the fluid end 108 and may, therefore, resist abrasive forces and/or resist corrosion which may result in a longer usable life, when compared to fluid ends without coating applied to sealing surfaces. As such, the sealing surfaces 132 of the fluid end 108 may include a longer usable life than sealing surfaces of fluid ends that do not include a hard coating that is applied to sealing surfaces. Furthermore, in some examples, as the coating 134 may wear over time, the coating 134 may be reapplied (or otherwise remanufactured) to the sealing surfaces 132 of the fluid end 108. As such, the coating 134 may be configured to wear before the sealing surfaces 132 of the block 120 of the fluid end 108, which may increase a usable life of a fluid end 108 and/or decrease downtime due to servicing a fluid end 108, among other potential benefits.

For example, the fluid end 108 may include a first sealing surface 132(1) that is located within the suction bore 122. The first sealing surface 132(1) includes a portion of the suction bore 122 where the seal 206 of the suction valve seat 204 contacts the block 120 (shown in FIG. 2 ). In FIG. 3 , the suction bore 122 includes an enlarged-diameter portion 122 a and a reduced-diameter portion 122 b extending downward therefrom (as in the figure), which direction may also be considered the upstream direction. Downstream from the enlarged-diameter portion 122 a is a neck portion 122 c, which is reduced in diameter relative to the enlarged-diameter portion 122 a. As shown in FIG. 3 , the first sealing surface 132(1) may comprise at least a portion of an inner cylindrical surface of the reduced-diameter portion 122 b. As described previously, fluid may, at times, flow between the seal 206 and the block 120, which may cause wear on the block 120 and may cause failure of the fluid end 108 due to a washboard failure (or other abrasive wear) of the block 120. As such, the coating 134 may be applied to the first sealing surface 132(1) such that the coating 134 is applied to the block 120 between the block 120 and the seal 206. As shown in the example of FIG. 3 , the coating 134 may be applied to the inner cylindrical surface of the reduced-diameter portion 122 b. In some examples, the coating 134 may be continuous in a circumferential direction about the inner cylindrical surface of the reduced-diameter portion 122 b. The coating 134 may be disposed radially outside the corresponding seal (e.g., seal 206 of the suction valve seat 204 shown in FIG. 2 ) and radially inside the inner cylindrical surface of the reduced-diameter portion 122 b. The coating 134 may prevent and/or inhibit wear on the block 120 at the first sealing surface 132(1) and may, therefore, extend a usable life of the fluid end 108.

Furthermore, the fluid end 108 may include a second sealing surface 132(2) that is located within the discharge bore 124. The second sealing surface 132(2) includes a portion of the discharge bore 124 where the seal 214 of the discharge valve seat 212 contacts the block 120 (shown in FIG. 2 ). In FIG. 3 , the discharge bore 124 includes an enlarged-diameter portion 124 a and a reduced-diameter portion 124 b extending downward therefrom (as in the figure), which direction may also be considered the upstream direction. Downstream from the enlarged-diameter portion 124 a is a neck portion 124 c, which is reduced in diameter relative to the enlarged-diameter portion 124 a. As shown in FIG. 3 , the second sealing surface 132(2) may comprise at least a portion of an inner cylindrical surface of the reduced-diameter portion 124 b. In some examples, the coating 134 may be applied to the second sealing surface 132(2) such that the coating 134 is applied to the block 120 between the block 120 and the seal 214. As shown in the example of FIG. 3 , the coating 134 may be applied to the inner cylindrical surface of the reduced-diameter portion 124 b. In some examples, the coating 134 may be continuous in a circumferential direction about the inner cylindrical surface of the reduced-diameter portion 124 b. The coating 134 may be disposed radially outside the corresponding seal (e.g., seal 214 of the discharge valve seat 212 shown in FIG. 2 ) and radially inside the inner cylindrical surface of the reduced-diameter portion 124 b. The fluid end 108 may also include a third sealing surface 132(3) that is located within the discharge bore 124. The third sealing surface 132(3) includes a portion of the discharge bore 124 where the discharge cover seal 220 contacts the block 120 (shown in FIG. 2 ). As shown in FIG. 3 , the third sealing surface 132(3) may comprise at least a portion of an inner cylindrical surface of the neck portion 124 c. In some examples, the coating 134 may be applied to the third sealing surface 132(3) such that the coating 134 is applied to the block 120 between the block 120 and the discharge cover seal 220. As shown in the example of FIG. 3 , the coating 134 may be applied to the inner cylindrical surface of the neck portion 124 c. In some examples, the coating 134 may be continuous in a circumferential direction about the inner cylindrical surface of the neck portion 124 c. The coating 134 may be disposed radially outside the corresponding seal (e.g., discharge cover seal 220 shown in FIG. 2 ) and radially inside the inner cylindrical surface of the neck portion 124 c.

The fluid end 108 may further include a fourth sealing surface 132(4) that is located within the plunger bore 126. The fourth sealing surface 132(4) includes a portion of the plunger bore 126 where the seal pack 222 contacts the block 120 (shown in FIG. 2 ). In FIG. 3 , the plunger bore 126 includes a packing bore 126 a and a reduced-diameter portion 126 b extending to the left therefrom (as in the figure). The packing bore 126 a may include an enlarged-diameter portion which may be sized to receive the packing seal 222. Further to the left (as in the figure), the reduced-diameter portion 126 b may be continuous with (e.g., having the same inner diameter as) an inner cylindrical surface of the pump chamber 130. As shown in FIG. 3 , the fourth sealing surface 132(4) may comprise at least a portion of an inner cylindrical surface of the packing bore 126 a. In some examples, the coating 134 may be applied to the fourth sealing surface 132(4) such that the coating 134 is applied to the block 120 between the block 120 and the seal pack 222. As shown in the example of FIG. 3 , the coating 134 may be applied to the inner cylindrical surface of the packing bore 126 a. In some examples, the coating 134 may be continuous in a circumferential direction about the inner cylindrical surface of the packing bore 126 a. The coating 134 may be disposed radially outside the corresponding seal (e.g., seal pack 222 shown in FIG. 2 ) and radially inside the inner cylindrical surface of the packing bore 126 a.

The fluid end 108 may also include a fifth sealing surface 132(5) that is located within the suction cover bore 128. The fifth sealing surface 132(5) includes a portion of the suction cover bore 128 where the suction cover seal 232 contacts the block 120 (shown in FIG. 2 ). In FIG. 3 , the suction cover bore 128 includes an enlarged-diameter portion 128 a and a reduced-diameter portion 128 b extending to the right therefrom (as in the figure). As shown in FIG. 3 , the fifth sealing surface 132(5) may comprise at least a portion of an inner cylindrical surface of the reduced-diameter portion 128 b. In some examples, the coating may be applied to the fifth sealing surface 132(5) such that the coating 134 is applied to the block 120 between the block 120 and the suction cover seal 232. As shown in the example of FIG. 3 , the coating 134 may be applied to the inner cylindrical surface of the reduced-diameter portion 128 b. In some examples, the coating 134 may be continuous in a circumferential direction about the inner cylindrical surface of the reduced-diameter portion 128 b. The coating 134 may be disposed radially outside the corresponding seal (e.g., suction cover seal 232 shown in FIG. 2 ) and radially inside the inner cylindrical surface of the reduced-diameter portion 128 b.

In some examples, by selectively applying the coating 134 to one or more of sealing surfaces 132(1)-132(5) between the respective seals and the block 120, the coating 134 may reduce wear on the block 120 while increasing the resistance of the sealing surfaces 132(1)-132(5) to erosive forces caused by pumping the fluid through the fluid end. As such, the coating 134 may extend the useful life of the block 120 of the fluid end 108 and/or down time due to maintenance may be decreased. Furthermore, the coating 134 may be reapplied to the sealing surfaces 132(1)-132(5), thereby further increasing a usable life of the block 120 of the fluid end 108.

FIG. 4 illustrates an example method 400 of coating portions of the fluid end 108. The fluid end 108 described herein may be better suited to resist corrosion, erosion, and/or abrasion than conventional fluid ends and may be cost effective to produce and/or to remanufacture. The method 400 shows some example steps for achieving such benefits. It is to be understood, that certain steps of the method 400 described herein may be conducted contemporaneously or sequentially. The order in which the operations are described is not intended to be construed as a limitation, and any number of the described steps may be performed in any order and/or the described steps may be combined in parallel to implement the process.

Specifically, at 402, the method 400 includes providing a block of a fluid end. In examples described herein, the block 120 includes a bare block without some and/or all of the components other than the block 120 of the fluid end 108.

At 404, the method 400 includes inserting a tool within one or more bores of the fluid end 108. The one or more bores include one or more of the suction bore 122, discharge bore 124, plunger bore 126, and/or the suction cover bore 128. In some coating processes, a tool may be stationary while a coated part is rotated around the tool. However, due to the size and weight of a block 120 of a fluid end 108, the tool used to coat portions of the block 120 may be rotated relative to the block 120, while the block 120 remains stationary during a coating process.

At 406, the method 400 includes applying the coating 134 to the desired surfaces. For example, the coating 134 may be applied to the sealing surfaces 132 (described previously) of the block 120. In the examples of FIGS. 1-3 , the operation 406 includes applying the coating 134 to each of the sealing surfaces (e.g., sealing surfaces 132(1)-132(5)). However, in some examples, the coating 134 may be applied to fewer than all of the sealing surfaces 132. Additionally, and/or alternatively, the coating 134 may be applied to additional surfaces, such as the pump chamber, other portions of the bores, or other surfaces. In some instances, the coating 134 may be a metal alloy powder applied using a thermal spray technique, such as HVAF, HVOF, or other thermal spray technique. Alternatively, the coating 134 may instead be plated to the above described surfaces. In some examples, the coating 134 may be a metal alloy powder including tungsten carbide.

At 408, the method 400 optionally includes finishing the surfaces to which the coating 134 was applied. In some examples, step 408 may be omitted as the natural surface finish (e.g., surface finish after step 406) of the coating process at 406 may be suitable. However, in some examples, the coated sealing surfaces 132 may be finished to ensure that the sealing surfaces 132 have a suitable surface finish. For instance, the coating 134 on the sealing surfaces 132 may be polished, buffed, washed, cleaned, or otherwise finished to ensure that the coating includes a desirable finish, (e.g., to ensure that the coating 134 does not include cracks, rough patches, or other inconsistencies that may be particularly disposed to erosion).

The method 400 allows for cost-effective and efficient manufacture of a fluid end, as detailed herein. For instance, because selected surfaces are coated, the fluid end 108 may be more resistant to corrosion, erosion, and/or abrasion. While the method 400 may include an additional step, e.g., the coating step, compared to conventional fabrication, the coating can meaningfully increase life expectancy of the fluid end 108 and/or the components thereof.

Furthermore, it is to be noted that the fluid end 108 may be remanufactured after the fluid end 108 has been operable for an amount of time. In such an example, the coating 134 may be reapplied to the sealing surfaces 132 according to the method 400 shown and described in FIG. 4 . In some examples, following step 402, the sealing surfaces 132 may be cleaned and/or the old coating may be stripped from the block 120. However, in some examples, such a cleaning step may not be necessary and anew coating may be applied directly to the old coating.

INDUSTRIAL APPLICABILITY

The present disclosure describes an improved fluid end (“fluid end”) and methods of making the fluid end. The fluid end may be used in a variety of applications. For example, the fluid end may be used in gas, oil, and hydraulic fracturing applications. The fluid end may be particularly useful in high pressure applications and/or with fluids containing abrasive particles. The disclosed fluid end may be in use for extended periods of time before failing and/or requiring replacement, which can result in a decrease in down time for fluid systems and/or reduce maintenance time and expense. Furthermore, the fluid end may be easily remanufactured to reapply a coating to the fluid end, further extending a usable life of the fluid end.

According to some embodiments, a fluid end 108 may include a coating 134 applied to sealing surfaces 132 of a block 120. By selectively applying the coating 134 to one or more of sealing surfaces 132, the useful life of the block 120 of the fluid end 108 may be significantly increased. Moreover, by purposefully excluding the coating 134 from other surfaces, deleterious effects can be avoided and/or cost associated with the coating 134 can be minimized while increasing wear resistance of the block 120

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof. 

What is claimed is:
 1. A fluid end comprising: a block; a suction bore formed in the block and having a suction valve disposed within the suction bore; a discharge bore formed in the block and having a discharge valve disposed within the discharge bore; a plunger bore formed in the block and having a plunger disposed therein, the plunger moveable within the plunger bore in a first direction and a second direction opposite the first direction such that the plunger directs fluid through the suction valve when the plunger moves in the first direction and directs fluid through the discharge valve when the plunger moves in the second direction; a seal pack disposed within the plunger bore and between the plunger and the block, thereby forming a fluid seal between the plunger and the block, the seal pack configured to maintain sealing contact with the plunger as the plunger moves in the first direction and the second direction; and a coating disposed on a surface of the block within the plunger bore between the seal pack and the block.
 2. The fluid end of claim 1, wherein the surface is a first surface and the fluid end further comprises: a discharge valve seat disposed within the discharge bore, wherein the discharge valve is configured to rest against the discharge valve seat when the discharge valve is closed; and an annular seal disposed between the discharge valve seat and the block, thereby providing a fluid seal between the discharge valve seat and the block, wherein the coating is disposed on a second surface of the block between the annular seal and the block.
 3. The fluid end of claim 1, wherein the surface is a first surface and the fluid end further comprises: a discharge cover disposed at least partially within the discharge bore; and an annular seal disposed between the discharge cover and the block, thereby providing a fluid seal between the discharge cover and the block, wherein the coating is disposed on a second surface of the block between the annular seal and the block.
 4. The fluid end of claim 1, wherein the surface is a first surface and the fluid end further comprises: a suction valve seat disposed within the suction bore, wherein the suction valve is configured to rest against the suction valve seat when the suction valve is closed; and an annular seal disposed between the suction valve seat and the block, wherein the coating is disposed on a second surface of the block between the annular seal and the block.
 5. The fluid end of claim 1, wherein the surface is a first surface and the fluid end further comprises: suction cover bore formed in the block; a suction cover disposed within the suction cover bore, wherein the suction cover includes a seal disposed between the suction cover and the block, wherein the coating is disposed on a second surface of the block between the seal and the block; and a suction cover retainer configured to secure the suction cover within the suction cover bore.
 6. The fluid end of claim 1, wherein the coating comprises a metal alloy and the coating is a thermal spray coating.
 7. The fluid end of claim 6, wherein the metal alloy comprises at least one of tungsten carbide, cobalt, or chromium.
 8. The fluid end of claim 6, wherein the thermal spray coating comprises a high velocity air fuel coating or a high velocity oxygen fuel coating.
 9. A fluid end comprising: a block; a suction bore formed in the block on a first axis; a discharge bore formed in the block on the first axis; a plunger bore formed in the block on a second axis that is substantially perpendicular to the first axis; a pump chamber formed at least partially between the suction bore, the discharge bore, and the plunger bore; a coating disposed on one or more surfaces of the block within at least one of a portion of the suction bore, a portion of the discharge bore, or a portion of the plunger bore.
 10. The fluid end of claim 9, wherein the pump chamber is substantially free of the coating.
 11. The fluid end of claim 9, further comprising: a discharge valve disposed within the discharge bore; a discharge valve seat disposed within the discharge bore, wherein the discharge valve is configured to rest against the discharge valve seat when the discharge valve is closed; and an annular seal disposed between the discharge valve seat and the block, thereby forming a fluid seal between the discharge valve seat and the block, wherein the coating is applied to at least a portion of the discharge bore between the annular seal and the block.
 12. The fluid end of claim 9, further comprising: a suction valve disposed within the suction bore; a suction valve seat disposed within the suction bore, wherein the suction valve is configured to rest against the suction valve seat when the suction valve is closed; and an annular seal disposed between the suction valve seat and the block, thereby forming a fluid seal between the suction valve seat and the block, wherein the coating is applied to at least a portion of the suction bore between the annular seal and the block.
 13. The fluid end of claim 9, further comprising: a plunger disposed within the plunger bore, the plunger being moveable in a first direction and a second direction opposite the first direction; and a seal pack configured to maintain sealing contact with the plunger as the plunger moves in the first direction and the second direction, wherein the coating is applied to at least a portion of the plunger bore between the seal pack and the block.
 14. The fluid end of claim 9, wherein the coating comprises a high velocity air fuel coating or a high velocity oxygen fuel coating.
 15. The fluid end of claim 9, wherein the coating comprises a metal alloy comprising at least one of tungsten carbide, cobalt, or chromium.
 16. A fluid system comprising: a fluid block; a plunger bore formed in the fluid block and having a plunger disposed at least partially within the plunger bore, the plunger being moveable in a first direction and a second direction opposite the first direction; one or more seals disposed within the plunger bore between the fluid block and the plunger, thereby forming a fluid seal between the plunger and the block, the one or more seals configured to maintain sealing contact with the plunger as the plunger moves in the first direction and the second direction; and a coating disposed on a surface of the fluid block between the one or more seals and the fluid block.
 17. The fluid system of claim 16, wherein the surface is a first surface and the fluid system further comprises: a suction bore formed in the fluid block; a suction valve seated within the suction bore; a suction valve seat disposed within the suction bore, wherein the suction valve is configured to rest against the suction valve seat when the suction valve is closed, and the suction valve is configured to open when the plunger moves in the first direction; and an O-ring disposed between the suction valve seat and the fluid block forming a fluid seal between the suction valve seat and the block, wherein the coating is disposed on a surface of the fluid block between the O-ring and the fluid block.
 18. The fluid system of claim 16, wherein the surface is a first surface and the fluid system further comprises: a discharge bore formed in the fluid block; a discharge valve seated within the discharge bore; a discharge valve seat disposed within the discharge bore, wherein the discharge valve is configured to rest against the discharge valve seat when the discharge valve is closed; and an O-ring disposed between the discharge valve seat and the fluid block forming a fluid seal between the discharge valve seat and the block, wherein the coating is disposed on a second surface of the fluid block between the O-ring and the fluid block.
 19. The fluid system of claim 16, wherein the plunger is coupled to a pump motor that drives the plunger in the first direction and the second direction.
 20. The fluid system of claim 16, wherein the coating comprises a high velocity air fuel coating or a high velocity oxygen fuel coating. 